1. Field of the Invention
The present invention relates to a liquid crystal display (LCD) panel and a manufacturing method thereof, and more particularly, to sealing structures suited for a process of liquid crystal dispenser method.
2. Description of the Related Art
A typical liquid crystal display (LCD) panel has a front substrate and a rear substrate with a liquid crystal interposed therebetween. More specifically, the front substrate is provided with a common electrode and a color filter, while the rear substrate is provided with an array of pixel electrodes connected to switching elements such as thin film transistors (TFTs).
FIG. 1 shows a first structural example of a liquid crystal display (LCD) panel according to the prior art. The LCD panel includes a rear substrate 101 with an array of pixel electrodes 11, a front substrate 201 with a color filter 12, a pair of alignment layers 4, a liquid crystal material 5, a spacer 6, and a sealing material 7.
The rear substrate 101 is a glass substrate provided with transparent pixel electrodes and an alignment layer 4. The front substrate 201 is a glass substrate provided with color filters 12 (R,G,B) and an alignment layer 4. The alignment layers 4 are provided for aligning molecules of the liquid crystal material 5 in a predetermined direction when an electric field is not applied to the molecules of the liquid crystal material 5.
The liquid crystal material 5 can be modulated by applying an electric field thereto when the driving voltage is applied between the pixel electrodes and a common electrode (not shown). The spacer 6 is arranged for keeping a cell gap between the rear substrate 101 and the front substrate 201 at a predetermined distance. The sealing material 7 is a material for sealing the liquid crystal material 5 within a display region (in this case, the display region is defined as a region covering all the pixel electrodes).
FIG. 2A is a plan view showing a bonding surface of the rear substrate at which surface the rear substrate and the front substrate, those substrates constituting the LCD panel of the first structure in the prior art, are bonded to each other. FIG. 2B is a cross-sectional view taken along a line X-Xxe2x80x2 shown in FIG. 2A. Furthermore, FIG. 3A is a plan view showing a bonding surface of the front substrate at which surface the rear substrate and the front substrate, those substrates constituting the LCD panel of the first structure in the prior art, are bonded to each other. FIG. 3B is a cross-sectional view taken along a line X-Xxe2x80x2 shown in FIG. 3A.
As shown in FIGS. 2A, 2B and FIGS. 3A, 3B, the LCD panel is formed in the following order.
(1) On the rear substrate 101, the array of pixel electrodes 11 and the alignment layer 4 are formed to provide a display region, and the sealing material 7 is provided on the outer circumference of the display region. Then, the liquid crystal material 5 is dropped on the alignment layer 4.
(2) In the front substrate 201, the color filter and the alignment layer 4 are formed to provide the display region, and the spacers 6 are distributed over the alignment layer 4.
(3) The rear substrate 101 and the front substrate 201 are overlapped with each other in a vacuum room, and then, the sealing material 7 is cured.
Note that in some cases, the sealing material 7 may be provided on the front substrate 201.
Furthermore, FIG. 4 shows a second structural example of the LCD panel in accordance with the prior art. The LCD panel includes the rear substrate 101, the front substrate 201, the alignment layer 4, the liquid crystal material 5, the spacer 6, the sealing material 7, and a sealant 8. The sealant 8 is a material for sealing an outlet 3 for surplus liquid crystal as shown in FIG. 5A, and is realized by employing UV-curing resin or the like.
FIG. 5A is a plan view showing a bonding surface of the rear substrate at which surface the rear substrate and the front substrate, those substrates constituting the LCD panel of the second structure in the prior art, are bonded to each other. FIG. 5B is a cross-sectional view taken along a line X-Xxe2x80x2 of FIG. 5A. Furthermore, FIG. 6A is a plan view showing a bonding surface of the front substrate at which surface the rear substrate and the front substrate, those substrates constituting the LCD panel of the second structure in the prior art, are bonded to each other. FIG. 6B is a cross-sectional view taken along a line X-Xxe2x80x2 of FIG. 6A.
As shown in FIGS. 5A, 5B and FIGS. 6A, 6B, and FIG. 7, the LCD panel is formed in accordance with the following procedure.
(1) In the rear substrate 101, the sealing material 7 is applied to the outer circumference of the display region such that the liquid crystal outlet 3 is formed, the alignment layer 4 is arranged in the display region, and the liquid crystal material 5 is dropped in the inside thereof.
(2) In the front substrate 201, the alignment layer 4 is arranged in the display region, and the spacer 6 is dispersed.
(3) The rear substrate 101 and the front substrate 201 are bonded to each other while being pressurized in the atmosphere, the excess liquid crystal material 5 is discharged from the liquid crystal outlet 3, and the sealing material 7 is hardened.
(4) A sealing operation is performed by applying the sealant 8 made of UV-curing resin or the like to the liquid crystal outlet 3 and hardening the sealant 8.
In the second structure, both the substrates can be bonded to each other in the atmosphere. Note that the sealing material 7 is applied to the front substrate 201 in some cases.
The LCD panel according to the prior art is formed in accordance with the above first or second structural example.
However, in the above LCD panel of the first structure according to the prior art, decompression (vacuuming) needs to be conducted in order to bond the rear substrate 101 and the front substrate 201 in a vacuum, and this operation is time-consuming. Furthermore, the liquid crystal material 5 dropped on the rear substrate 101 is not discharged but sandwiched by both the substrates in the structure, and thus, precision in the drop amount of the liquid crystal is required.
Furthermore, in the above LCD panel of the second structure according to the prior art, the operation for sealing the liquid crystal outlet 3 needs to be conducted.
Moreover, as to the LCD panel according to the prior art, both the first and second structures make the sealing material 7 thereof directly contact the liquid crystal material 5, and thus, deterioration and contamination of the liquid crystal material 5 occur owing to the sealing material 7. Furthermore, since the rear substrate 101 and the front substrate 201 are bonded to each other by the sealing material 7, the amount of the sealing material for the height corresponding to the diameter of the spacer 6 is required, which disadvantageously makes the amount of the sealing material 7 to be consumed large.
That is, there have been the following problems of the LCD panel according to the prior art.
(1) The decompression process makes the whole manufacturing process long in the manufacture of the LCD panel because decompression is time-consuming.
(2) Since high precision in the drop amount of the liquid crystal is required, the process of dropping the liquid crystal is long in the manufacture of the LCD panel.
(3) The sealing process needs to be performed.
(4) The usage amount of the sealing material is large.
(5) Since the liquid crystal material and the sealing material contact each other, the liquid crystal material is contaminated/deteriorated.
The present invention has been conceived in view of the above-mentioned problems, and therefore has an object to provide a LCD panel which can be formed without necessity for a sealing operation in the atmospheric pressure and with less amount of a sealing material, and to provide a manufacturing method thereof.
In order to achieve the above object, the present invention provides the following LCD panel as a first aspect. That is, the LCD panel includes: a liquid crystal layer sandwiched between a first substrate and a second substrate, a first partition wall on the first substrate, a second partition wall on the second substrate and a sealing member on the second partition wall. In more detail, the first partition wall is formed on the first substrate for defining a display region by surrounding the liquid crystal layer and provided with at least one opening to allow an overflow of an excess liquid crystal, and the second partition wall is formed lower than the first partition wall on the second substrate so as to surround the first partition wall and form a gap between the first substrate and the second partition wall partition wall, and further, a sealing member is provided on the second partition wall so as to seal the gap between the first substrate and the second partition wall.
According to the first aspect of the present invention, since the sealing material is disposed only on the tip end of the second partition wall, and is used in order to fill a fraction of the gap in the outer circumference between the first substrate and the second substrate, the amount of the sealing material to be consumed can be reduced.
Additionally, in order to achieve the above object, the present invention provides the following method for manufacturing a LCD panel as a second aspect. That is, the method for manufacturing a liquid crystal display panel, includes forming a first partition wall on a first substrate for defining a display region, the first partition wall being provided with at least one opening, and forming a second partition wall on a second substrate so as to surround the first partition wall, the second partition wall being lower than the first partition wall to form a gap between the first substrate and the second partition wall partition wall. The method further includes providing a sealing member on the second partition wall so as to seal the gap between the first substrate and the second partition wall, dropping liquid crystal onto a portion of the display region of the first substrate within the first partition wall, the portion being remote from the at least one opening of the first partition wall, bonding the first substrate and the second substrate while discharging a surplus liquid crystal from the at least one opening, and hardening the sealing material while pressurizing over the first substrate and the second substrate.
According to the second aspect of the present invention which is characterized as above, the bonding is conducted while the liquid crystal is discharged from the at least one opening as a liquid crystal outlet, whereby there is no need to enhance precision in the amount of the liquid crystal to be dropped to fill up the space enclosed by the first substrate, the second substrate, and the first partition wall.
Furthermore, since the liquid crystal can be diffused over the display region by utilizing surface tension, decompression does not need to be performed. Moreover, the liquid crystal outlet can be sealed by the second partition wall the moment the bonding of the rear substrate and the front substrate is completed. Thus, a sealing operation does not need to be performed.
In the above first and second aspects of the present invention, when the at least one opening constitutes a plurality of openings, it is preferable to provide at least one of the plurality of openings in the vicinity of a corner of the display region of the first substrate. Thus, the air does not remain at the corner portion of the display region.
Furthermore, it is preferable to have the first and second partition walls formed by a photoetching method. Thus, the first and second partition walls can be easily formed with a uniform height.